AQA A LEVEL CHEMISTRY PAPER 1 QUESTIONS AND ANSWERS WITH SOLUTIONS 2024 TOF steps - ANSWER 1) ionisation 2) acceleration 3) ion drift 4) detection 5) analysis Electron impact - ANSWER Sample vaporised and electron gun fires high energy electrons at it which knock off 1 electron from each particle, making them 1+ ions NB- can knock off more than one e or break molecular ion electrospray ionization - ANSWER Sample dissolved in volatile solvent then injected through needle to give fine mist which is attached to positive end of high voltage power supply, particles gain proton NB- Mr of substance is actually one less than shown due to extra H+ Acceleration (TOF) - ANSWER positive ions accelerated using electric field so they all have the same kinetic energy Ion drift (TOF) - ANSWER particles with small mass have larger velocity do ions start to separate with lightest ions reaching detector first Detection (TOF) - ANSWER positive ions hit negatively charged plate and gain an electron which forms a current, the larger the current the higher the abundance Analysis (TOF) - ANSWER -computer uses data to produce mass spectrum which shows mass m / charge z ratio -mr or ar is furthest right peak (small peaks larger than mr are due to isotopes) -may be large peaks at lower mr due to fragmentation Electron spin - ANSWER Property of electron (CW or ACW) Represented by up and down arrows Orbitals - ANSWER Defined regions of space around nucleus where electrons most likely to be found, each orbital holds 2 electrons Hund's Rule - ANSWER Electrons prefer to occupy orbitals on their own and only pair up when no empty or bait ask of same energy are available Electron configuration - ANSWER 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 4d10 exceptions to electron configuration - ANSWER chromium and copper, only take one electron in 4s orbital Why does ionization energy decrease down a group? - ANSWER Atoms get bigger so electrons further away from nucleus, greater shielding Why does ionization energy increase across a period? - ANSWER Atoms get smaller, nuclear charge increases, similar shielding Dip in ionisation energy groups 2 -3 - ANSWER Electrons take up higher orbital (s to p) which makes ionisation energy lower as higher orbitals have higher energy Dip in ionisation energy groups 5 -6 - ANSWER Electron - electron repulsion in orbital makes electron easier to lose Relative atomic mass - ANSWER The average mass of an atom of an element/ 1/12th of the mass of an atom of carbon -12 Empirical formula - ANSWER The simplest whole number ratio of atoms of each element present in a compound
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